A fuser device used in an electrophotographic image forming apparatus may use an endless fuser belt. Disclosed in Patent Document 1 is a fuser device that rotatably holds a fuser belt by a flange-shaped holding member installed on the inner circumferential side of the fuser belt. Also, in order to regulate the width-direction displacement of the fuser belt, driven ring are disposed on both sides in the width direction of the fuser belt. The driven rings contact with the width-direction ends of the fuser belt and rotate following the fuser belt.